1. Field of the Invention
This invention relates to the field of energy saving devices which energize and deenergize the electrical loads in a room or in a building when such loads are not required to be in use. Specifically, the invention relates to an optoelectronic switching device which is actuated by an encoded photoelectric switching card which can be inserted in and removed from a card switching box to energize and deenergize HVAC and nonHVAC electrical loads responsive to the switching device. The present invention also comprises an HVAC cycling circuit capable of cycling the HVAC power loads on and off while the nonHVAC loads remain off, thereby providing continued climate control in a room or building where the HVAC systems operate.
2. Description of the Prior Art
A variety of electronic and electromechanical devices have been used to energize and deenergize the electrical loads in a room or building for energy conservation purposes. Many such devices have been designed for application in the hotel/motel industry where guests have been known to leave rooms unoccupied with the lights and other electrical fixtures or systems left on. Such fixtures or systems may include televisions, radios, and heating, ventilating and air-conditioning (HVAC) systems.
A number of prior art switching devices have been designed to energize and deenergize the electrical loads in a room when a person enters or leaves the room. Many of these devices contain a switching device whose actuation is, in whole or in part, dependent upon the operation of a deadbolt or latch. Such devices are disclosed in U.S. Pat. No. 4,580,740 to Dalton et al.; U.S. Pat. No. 4,091,866 to Curatolo; U.S. Pat. No. 4,391,406 to Fried; and U.S. Pat. No. 4,333,604 to Petrillo.
Such deadbolt/latch switching devices have several drawbacks. One drawback is that the electromechanical coupling within the deadbolt/latch device may wear out or malfunction after repeated engagement and disengagement of the latch or deadbolt. Another drawback is that the intended purpose of such systems can be defeated by relatively simple acts, such as stuffing paper or chewing gum in the latch/deadbolt assembly. Another major drawback of deadbolt/latch systems is that in many cases, the room occupant must lock the door after he enters the room. In situations where a room occupant is occupying the room and merely wishes to briefly open his door to look outside or to speak with someone, he must relock the door after it is closed. This can prove to be an annoyance for many room occupants who do not wish to be burdened with relocking their door every time they close it.
Other prior art devices rely upon transmitters and receivers utilizing ultrasonic or radio signals to actuate one or more switches coupled to the energy loads of the room or building. Such devices are disclosed in U.S. Pat. No. 4,150,415 to Fichtner; U.S. Pat. No. 4,223,301 to Grimes et al.; and U.S. Pat. No. 4,101,886 to Grimes et al. The performance of such systems may be adversely affected by stray ultrasonic or radio signals, such as signals from garage door opener transmitters. Also, if a physical object is placed in the room in the path of the ultrasonic or radio signal, such physical object may sufficiently attenuate the signal to adversely affect system operation. Furthermore, the transmission and receiving hardware associated with such systems makes such systems expensive to install and maintain.
Other prior art devices such as those disclosed in U.S. Pat. No. 5,206,521 to Ruiz, et al., merely disclose an optoelectronic system for energizing and deenergizing one set of electrical loads that are electrically coupled to an optoelectronic switching device. Such a system has several drawbacks in practical applications such as a hotel room or other location designed primarily for human habitation. In most situations, the majority of electrical usage in a hotel room or other similar location is for heating, ventilating, and air-conditioning (HVAC), as opposed to lighting, television, and small appliances. Prior art devices fail to provide an energy savings system that deenergizes all nonHVAC electrical loads when the occupant is absent from the room and also periodically energizes and deenergizes HVAC electrical loads to maintain a comfortable climate in the room and conserve energy.
A drawback of the type of system disclosed in U.S. Pat. No. 5,206,521 is that all HVAC loads are deenergized for the duration that the occupant is absent from the room if these loads are controlled by the optoelectronic switching system. For long absences during hot weather, this can result in the room being uncomfortably warm when the occupant returns, thereby requiring an undesirably long cooling period when the HVAC loads are reenergized, before the room is comfortable again. The situation is undesirable. A similar drawback exists during cold weather, requiring an undesirably long heating period when the occupant returns, before the room is comfortable again.